Thermostatically engaged clutch



April 6, 1954 E. H. WHITE THERMOSTATICALLY ENGAGED CLUTCH 2 Sheets-Sheet1 Original Filed Nov. 25, 1946 RE m T m W H T T E R E. V E

ATTORNEY April 6, 1954 E. H. WHITE 2,674,353

THERMOSTATICALLY ENGAGED CLUTCH Original Filed Nov. 25, 1946 2Sheets-Sheet 2 INVENTOR EVERETT H, WHITE BY )0. H @M ATTORNEY PatentedApr. 6, 1954 2,674,358 vTHEBMOSTATICALLY ENGAGED CLUTCH Everett H.White, St. Paul, Minn.

Original application November 25, 1946, Serial No. 712,059. Divided andthis application February 20, 1950, Serial No. 145,265

9 Claims.

This application is a division of my pending application Serial. No.712,059, for an Air Conditioning System, filed November 25, 1946, andnow Patent 2,509,948, granted May 30, 1950.

The invention herein has relation to a blower control through theinstrumentality of which velocity and volume of air forced to andthrough a hood or plenum chamber of'an air conditioning system can beprogressively and accurately controlled and regulated through a range ofvalues win response to the temperature in such hood or plenum chamber.

Objects of the invention are to provide a blower control which willinclude a multiple speed drive for a fan or blower of an airconditioning system adapted to cause air to be forced to and through ahood or plenum chamber of said air conditioning system and a novel andimproved construction and arrangement whereby the velocity and volume ofair forced to and through said hood or plenum chamber can beprogressively and accurately controlled through a selected range ofvalues, from zero to maximum as disclosed, by adjustment of saidmultiple speed drive in response to the'temperature in such hood orplenum chamber, and also include a novel and improved construction andarrangement whereby said range of values selectively can be altered atwill.

A further object is to provide in the blowercontrol novel and improvedmechanism through the instrumentality of which the speed of rotation ofa fan or blower of an air conditioning system can be controllablyaltered in response to changes in temperature of a heat responsiveelement of said air conditioning system.

And a further object is to provide in the blower control variousdesirable and improved features and characteristics of constructionwhich will be novel both as individual entities of said blower controland in combination with each other.

In the accompanying drawings forming a part of this specification, v p rFig. l is a central sectional view of a blower control made according tothe invention;

Fig. 2 is an end elevational view,'on a reduced scale, of the blowercontrol disclosed in Fig. 1, showing said blower control as it wouldappear from the right side in said Fig. 1;

Fig. 3 is a detail sectional view, taken as on" line 3-3 in Fig.1; and 0Fig. 4. is a detail sectional view, on a reduced scale, taken as on line4-4 in Fig. 1.

The new and improved blower control is adapted to be employed toalterably control and regulate operation of a blower (not shown) of anair conditioning system in response to changes in temperature of a heatresponsive element (also not shown) of said air conditioning system.Said blower ordinarily will be driven by an electric motor (not shown)of the air conditioning system through the medium of a belt (not shown)ridable upon a pulley fixed upon a driving shaft of said blower and alsoridable upon an adjustable V-pulley ll] of the blower control which isrigid with a self-oiling bushing H revoluble and slidable upon a shaftE2 of said blower control to be driven by said electric motor. The shaftl2 includes a central opening is, which extends longitudinally throughsaid shaft, in the inner end portion of which the electric motor shaftI4 is adapted to be rigidly secured, as by a set screw I 5, and theshaft l2 also includes an internal thread l6 which bounds the outer endportion of said central opening it.

Said shaft 12 driven by the electric motor integrally supports anannular element ll, situated at the inner side of the V-pulley it, andan annular friction disc l8, in surrounding relation to the shaft I2,has a fiat inner surface thereof arranged in contiguous relation to afiat outer surface of the annular element ll disposed in a planeperpendicular to the axis of the shaft I2 and a fiat outer surfacethereof arranged incontiguous relation to a fiat inner surface of theV-pulley If! disposed in a plane perpendicular to said shaft l2. Thatis, the annular friction disc 18 is situated between the annular elementI! and the adjustable V-pulley It. It may be fixed to either saidannular element or to said V-pulley, but not to both.

A hollow fixture I9 is threadably received in the internal thread 16 ofthe shaft l2 driven by the electric motor, and said hollow fixture it ismounted in a fixedly supported bearing it situated in spaced relation tosaid electric motor. The hollow fixture l9 includes a reduced inner endportion 2| having an external thread 22 received in the internal threadIt in such manner that an internal circumferential surface of saidhollow fixture'is fitted up against the adjacent end of the shaft i2,and the hollow fixture includes a reduced outer end portion rotatablymounted in the bearing 26. Said hollow fixture l9 also includes anintermediate portion 1350f cross-sectional dimension as shown aboutequal to the cross-sectional dimensionof the reduced end portion 2|. Thehollow fixture it and the parts rigid therewith are adapted to berotated in-thebearing 20," and the construction arrangement will be suchthat there will be no longitudinal movement of the hollow fixturerelative to said bearing.

A block 26 of insulating material, situated at the outer side of thebearing 28, is fixed, as by screw bolts 21, to said bearing 20 upagainst a washer situated between the bearing and said block '26.

A plurality of separate and independent bimetallic strips, each denoted28 and of general U-shaped, are supported in spaced apart relation toeach other upon and about the hollow fixture I9. Each of the bi-metallicstrips 28 includes an outer arm 29 thereof which has its interior freeend portion 30 engaged against an annular shoulder 3|, provided by aninsulating block 32 fixed, as by a screw bolt 33, upon the intermediateportion 25 of the 'hollow fixture l9, and situated between said annularshoulder 3| and an annular insulating member 34 fixed upon andperpendicular to .the reduced outer :end portion 24 of said hollowfixture. The construction and arrangement will be such that the interiorfree end portions 39 of the outerarms .29 f the bimetallic strips 28will .be graspedIand rigidly held between theannularshoulder 3| and theannular insulating member .34. Each 'bi-metallic strip 28 also includesan inner arm .35 thereof which issituated inspaced, alined relation ,tothe outer arm.29, and the'outer .and inner arms 29 and 35 are integrallyconnected at the base 39 of each .bi-metallic .strip 28. Each base 39 issituated exteriorlyof saidouter and inner arms 29 and 35. .Anannular:fiange 31 upon the exterior margin of th annular :insulating member 34is as disclosed in spaced, overlying relation to the bases :36 .of thebi-zmetallic strips 28.

Spaced apart openings .38 through the annular insulating member 34, inspaced, surrounding relation to .the hollow fixture l9, are inadjacentrelation to the outer arm 29 of the bi-metallic strip 28, anda closureplate 39 for said spaced apart openings 38 is adjustably supported uponthe outer surface of, said annular'insulating member 34. The .closureplate ;39 includes spaced apart, elongated, arc shape slots 4|! adaptedto receiveset screws 4| threaded into the annular insulating member 34,and said closure plate also includes spaced apart openings 42 adapted tobe alined or partially alined with the spaced apart openings 38 'in saidannular insulating member. The construction and arrangement will be suchthat theclosure plate 39 can be rotatably adjusted relative to theannular insulating member.34 thus .to-adjust and regulate the sizes ofthe passages for air, each constituted as an opening .38 and an opening42, through said closure plate and annular insulating member. Theannular flange .31 rigidly supports spaced apart, interiorly situatedfan blades 43 which are in adjacent relation to the inner arms 35 of thebi-metallicstrips 28, at the side of said bi-metallic stripsopposite-the spaced apart openings 38 and 42. An annular plate on theannular flange 31 at the inner sides of the fan blades 43, or side ofsaid fan blades spaced from the annular insulating member 34, is denoted44, and said annular flange 31 is open .at locations between said fanblades 43 and exterior thereto. As disclosed, the annular plate 44 issecured to the annular flange 31 by screw bolts 45.

A resistance element 46, constituted as a resistance wire in mica,issuitably and conveniently supported, as at 41, upon the inner endof acontact screw 48 insulatively fixed-within the hollow strips and, at thesame time,

fixture l9 and is situated between the outer and inner arms 29 and 35 ofthe bi-metallic strips 28 in surrounding relation to said hollow fixturel9. Enamel-like, annular discs, denoted 49 and 59, respectively, liebetween the resistance Wire in mica and the outer and inner arms 29 and35 of the bi-metallic strips 28, in spaced, surrounding relation to thehollow fixture. The annular discs 49 and 50 are adapted to electricallyinsulate the resistance wire from the bi-metallic permit heat from saidresistance wire to be absorbed by said bimetallic strips. Statedotherwise, said annular discs 49 and 50 are electrical currentresistors, but not heat resistors.

The inner arm 35 of each bi-metallic strip 28 includes an interior freeend portion 5| which is bent inwardly toward and alined with theself-oiling bushing II, and the interior free end portions 5| all lie ina single circumference which is concentric to the shaft |2 driven by theelectric motor. The inner free ends 52 of said interior free endportions 5| all terminate in a single plane perpendicular to the axis ofthe shaft l2, and the bi-metallic strips 28 together constitute a thrustentity of the blower control.

A thrust ring 53, slidably situated upon an outer end portion of theshaft l2 driven by the electric motor between the interior free endportions 5| of the inner arms 35 of the bi-metallic strips 28 and theouter end of the self-oiling bushing is retained upon said shaft I2 bythe circumferential shoulder 23 provided by the hollow fixture l9 at theouter side of said thrust ring 53.

The resistance element 46 is adapted. to be energized by electric energythus to cause the outer and inner arms 29 and 35 of the bi-metallicstrips 28, respectively, to become gradually spaced farther and fartherapart and the V-pulley ID, the annular friction disc l8 and the annularelement I! to be clutched together. The construction and arrangementwill be such that said bi-metallic strips will exert no appreciablepressure against the thrust ring 53 when said resistance element 48 isdeenergized, so that the V- pulley ID, the annular element I! and theannular frictiondisc l8 will be under insuflicient pressure to causerotation of said V-pulley l0 and the blower driving shaft to occur whenthe shaft I2 is set in operation in response to operation of theelectric motor while the resistance element 46 is deenergized. In apractical embodiment of the invention, said resistance element48 willbecome energized, in response to rise of temperature in the hood orplenum chamber of an air conditioning system in connection with whichthe blower control is employed, after theelectric motor is set inoperation. More explicitly stated, a heat responsive element of said airconditioning system is adapted to be actuated as the temperature risesin said hood or plenum chamber, while said electric motor is operating,to cause a circuit including the resistance element 45 to be closed thusto cause said resistance element to be energized. As the energizedresistance element 46causes the bi-metallic strips 28 to be heated up,the outer and inner arms 29 and 35 of the separate and independentbi-metallic strips 28, respectively, become gradually spaced apart byprogressively increasing heat applied to said bi-metallic strips, andthe thrust ring 53 becomes actuated inwardly, toward the left in Fig. 1,thus tocause the V-pulley l0 to be moved toward the annular frictiondisc l8 and themnular' element'll'. stated otherwise, with increase inpressure exerted by the bi-metallic strips 28 against the thrust ring53, the annular friction disc I8 is more tightlygrasped between theV-pulley Wand the annular element l1, and vice versa. As the frictionbetween said V-pulley, annular friction disc and annular element becomesgreat enough to cause the V-pulley with the bushing H to be turned inresponse to rotationof the shaft driven by the electric motor, saidV-pulley,. together with the hollow fixture l9 and parts rigidtherewith, is rotated thus to cause the blower driving shaft, connectedwith the V-pulley ID by a belt, to be rotated. Some slippage occursbetween the annular friction disc I 8 and the parts engaged with saidannular friction disc throughout the entire range of blower speed up tothe point where pressure exerted by the bi-metallic strips 28 causessaid annular friction disc to be tightly grasped, and then the V-pulleyI I3 and the blower driving shaft are driven at the full speed of theelectric motor driven shaft 52.

The heat responsive element of an air conditioning system in connectionwith which the blower control is employed can be constituted as alei-metallic helix situated in the hood or plenum chamber of said airconditioning system and constructed and arranged to cause a circuitincluding the resistance element 46 to be closed in response to rise oftemperature in said hood or plenum chamber. Said circuit can include aspart thereof a terminal 54 suitably and conveniently supported upon theinsulating block it and grounded to the bearing 20, a conductor 55extending from one of the bi-metallic strips 28, which lei-metallicstrip is grounded to the thrust ring 55%, etc., to the resistance wireof the resistance element d5, a conductor 55 extending from saidresistance wire to the contact screw t8, and a terminal 57 suitably andconveniently supported upon said insulating block 26 and conductivelyengaged with the outer end of said contact screw &8.

Closing the circuit including the resistance element at, which circuitis traced from the terminal 54 to ground, thence from ground through theconductor 55, said resistance element 46, the conductor t and thecontact screw 48 to the terminal 5?, Will causesaid resistance elementto be heated and the bi-metallic strips 28 to absorb heat. The arms ofsaid oi-metallic strip Will have tendency to move apart gradually andprogressively when heated by the resistance element 48, and since theouter arms 29 of the bi-metallic strips are anchored, the inner arms 35of said bi-metallic strips will be forced inwardly thus to cause thespeed of rotation of the blower to be altered in the manner and with theresult as hereinbefore set forth. It will be apparent that th heatresponsive element of the air conditioning system can .be set to causethe circuit including the resistance element 46 to be closed when thetemperature of air in said hood or plenum chamber has any value whichmay be selected.

Attention is called to the fact that the layer of metal at the interiorside of each bi-metallio strip 28 has 'a greater coefficient ofexpansion than the layer of metal at the exterior side of the bimetallicstrip. Thus, the resistance element 46 applies its heat directly to themore expansible metal and the spreading action of the arms of thebimetallic strip is positive and relatively quick.

It will be evident that the construction and arrangement can be suchthat the speed of rotation of the blower'can beincieasd from'zero speedto maximum speed, and decreased from maximum speed to zero speedinany'intervalof time whic may be selected. It is obvious that the timeperiod will depend upon various factors surrounding the bi-metallicstrip 28, the resistance element 46, etc., and the characteristics ofthe electrical energy employed. By way of example, an installationinherently can'includeprovision for increase of speed of the bloweremployed from zero speed to maximum speed in three minutes, more orless.

The construction and arrangement; including the spaced apart openings 38and 42, the fan blades etc., obviously constitutes means through theinstrumentality of which increase of speed of rotation of the blower inany interval of time which may be predetermined can be accuratelycontrollably accomplished. Desirably, the electric motor employed can bea substantially constant speed motor. The motor driven shaft l2 and theparts rigid with said motor driven shaft, including a force unitconsisting of the bimetallic strips'ZB, the resistanc element 46, thehollow fixture it, the insulating block 32, the annular insulatingmember 34 and its fan blades 43, etc., are assembled with the electricmotor shaft i l to be continuously rotated at the speed of said motorshaft at all times while the electric motor is in operation. Theconstruction and arrange ment will be such that air will be drawn orsucked by the fan blades 43 through the spaced apart openings 38 and 42over the bi-metallic strips 28 and radially out of theunit constitutingthe blower control at the side of said bi-metallic strips its oppositesaid spaced apart openings at and 52. It will be evident that byadjustment of the closure plate 39 thus to adjust and regulate the sizesof the passages for air through said closure plat and the annularinsulating member 34, by way of the spaced apart openings 38 and 42, thetemperature within the blower control in surrounding relation to thebi-metallic strips 28 can be kept at any substantially constant valuewhich may be selected. Thesmaller the sizes of the passages for air, thehigher the temperature constantly maintained at the location of andabout the bi-metallic strips, and the larger the sizes of said passagesfor air, the lower the overall temperature at and about said bi-metallicstrips.

Upon the fall of temperature in the hood or plenum chamber of an airconditioning system in connection with which the new and improved blowercontrol is employed to a temperature causing the heat responsive elementto open the circuit including the resistance element 46, said resistanceelement of course will become deenergized and lose heat thus to causethe bimetallic strips 28 to become contracted and release the annularfriction disc IE to permit the blower to come to rest.

No matter what may be the actual temperature in the hood or plenumchamber, or whether the heating plant or furnace is heating'up orcooling on", operation of the blower will be inresponse to temperatureof air in said hood or plenum chamber. The velocity and volume of airforced to and through the hood of plenumchamber will be progressivelyand accurately controlled and regulated through a selected range ofvalues, predetermined by the construction and arrangement of thebimetallic strips 28, the resistance element 46, etc., etc., and theelectrical energy employed, by adjustment of the multiple speed driv inresponse to the temperature in the hood or plenum chamopenings 38 and142, etc., constitute means whereby increase of speed of :rotationofthe'blower in any. predetermined interval of time which may be selectedcan ,be accurately controllably accomplished.

What is claimed is:

1. In a device of the character described, a shaft to be-driven, anelement longitudinally. slidable and, freely rotatable onsaid shaft, avariable speedzdriveincluding frictionally engaged members upon theshaft for connecting said shaft to said element andmechanism fixed tosaid shaft to rotate therewith adapted-to be thermostatically expandedto causesaid variable speed drive to rotate said element athigherspeeds. and to be thermostatically contracted to cause the variablespeed drive to rotate said element atlower speeds, and electricalresistancemeans uponsaid shaft and fixed to rotate with saidmechanismfor causing the mechanism to be heated.

.2. The combination as specifiedin claim 1, and manually adjustablemeansupon said shaft and fixed to rotate with said mechanism andelectrical resistance meansfor causing the rate of friction of saidvariable speed drive due to temperature changes of said mechanismselectively to be varied.

3. The combination as specified in claim 1, and means including fanblades and manually adjustable air passages upon said shaft and fixed torotate with saidmechanism and electrical resistance means for causingair in predetermined amount constantly to travel past said mechanism andelectrical resistance means.

4. In a machine of the character described, a shaft to be drivenincluding a first clutching surface, anelement freely rotatable on saidshaft including a second clutching surface, and mechanism fixed uponsaid shaft constituted as resistance heating means and temperatureresponslvemeans adapted to be expandedin response to rise of temperatureto operate said second clutching surfacetowardsaid first clutchingsurface to cause said element to be rotated at higher speeds and to becontracted in response to fall of temperature to-permit the secondclutching surface to be moved away from the first clutching surface tocause the element to be rotated at lower speeds, and manually adjustablemeansfixed upon said shaft to rotate therewith and with said mechanismfor causing air in predetermined amount constantly to travel past saidresistance heating means and said temperature responsive means.

5. In a device of the character described, a shaft to be driven, anelement longitudinally slidable and freely rotatable on said shaft, avariable speed drive including frictionally engaged members forconnecting said shaft to said element, heat responsive mechanismincluding an expansible and contractible member rotatable with said.shaft and operable to alter the friction of said drive thus to alterthe speed of rotation of said element in response to changes intemperature of said heat responsive mechanism, and manually adjustablemeans fixed upon said shaft to rotate therewith for causing the rate ofalteration. of thefriction. of said drive due to temperavber.Clearly/the fan. blades :43,-the spaced-apart -6.:In a device of thecharacter described, a

shaftto be driven,.an element-freely rotatable on said shaft, a.variable speed drive including frictionally engaged .members forconnecting said ,shaftto said element; heat responsivemechanismincluding aniexpansible and contractible member rotatable with saidshaft. and operable to alter the friction of said-drive thus toalter'the speed of rotation of said element in response to changes intemperature of said heat responsive mechanism, and manually adjustablemeans fixed upon said shaft to rotate therewith, and with saidiheatresponsive mechanism. for causingthe rate of a1- terationof thefrictionof said drive due to temperature changes ,of said expansible :andcontractible 1 member selectively to be .varied.

'7. In a machine of the character described, a shaft to be drivenincluding a first clutching surface, an element freely rotatable on saidshaft including asecond clutching Surfaceandmechanism fixed upon saidshaft atthe side of said second clutching surface .opposite said firstclutching surface constituted as resistance heating means andbi-metallic strips disposed in surrounding relation to and each bent toloop form about said resistance heating means adapted to be expanded inresponse to rise of temperature to operate said second clutching surfacetoward said first clutching surface to cause said element to be rotatedat higher speeds and to be contracted in response to fall of temperatureto permit the second clutching surface'to be moved away from the firstclutching surface to'cause the element to be rotated at lower speeds,each ofsaid bi-metallic strips including a first arm at a side of theresistance heating means adjacent the first and second clutchingsurfaces and a second arm anchored to said shaft at a side of saidresistance heating means opposite said first and second clutchingsurfaces.

8. The combination as specified in claim 7, and adjustable meansrotatable with said mechanism for causing air in predetermined amountconstantly to travel past said resistance heating means and saidbi-metallic strips.

9. The combination as specified in claim '7, and means including fanblades and manually adjustable air passages rotatable with said shaft.and said mechanism for causing air in predetermined amount constantlyto travel past said resistance heating means and said bimetallic strips.

References Cited in the -file of this patent UNITED STATES PATENTSNumber Name Date 2,005,465 Modine June 18, 1935 2,021,413 Gille Nov. 19,1935 2,090,401 Mayo Aug. 17, 1937 2,308,507 Hallinan Jan. 19, 19432,320,900 Waltz June 1, 1943 2,322,405 White June 22, 1943 2,369,681Miles Feb. 20, 1945 2,471,924 Bolesky May 31, 1949 2,498,259 Elmer Feb.21, 1950 2,502,461 Kane Apr. 4, 1950

